Genetic structure at range edge: Low diversity and high inbreeding in Southeast Asian mangrove (Avicennia marina) populations

S. Arnaud-Haond*, S. Teixeira, S. I. Massa, C. Billot, P. Saenger, G. Coupland, Carlos Duarte, E. A. Serrão

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

140 Scopus citations

Abstract

Understanding the genetic composition and mating systems of edge populations provides important insights into the environmental and demographic factors shaping species' distribution ranges. We analysed samples of the mangrove Avicennia marina from Vietnam, northern Philippines and Australia, with microsatellite markers. We compared genetic diversity and structure in edge (Southeast Asia, and Southern Australia) and core (North and Eastern Australia) populations, and also compared our results with previously published data from core and southern edge populations. Comparisons highlighted significantly reduced gene diversity and higher genetic structure in both margins compared to core populations, which can be attributed to very low effective population size, pollinator scarcity and high environmental pressure at distribution margins. The estimated level of inbreeding was significantly higher in northeastern populations compared to core and southern populations. This suggests that despite the high genetic load usually associated with inbreeding, inbreeding or even selfing may be advantageous in margin habitats due to the possible advantages of reproductive assurance, or local adaptation. The very high level of genetic structure and inbreeding show that populations of A. marina are functioning as independent evolutionary units more than as components of a metapopulation system connected by gene flow. The combinations of those characteristics make these peripheral populations likely to develop local adaptations and therefore to be of particular interest for conservation strategies as well as for adaptation to possible future environmental changes.

Original languageEnglish (US)
Pages (from-to)3515-3525
Number of pages11
JournalMolecular Ecology
Volume15
Issue number12
DOIs
StatePublished - Oct 1 2006

Keywords

  • Avicennia marina
  • Biogeographic limits
  • Genetic diversity
  • Mangrove
  • Mating system
  • Species' distribution margins

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics

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